/*
 * Title:        CloudSim Toolkit
 * Description:  CloudSim (Cloud Simulation) Toolkit for Modeling and Simulation of Clouds
 * Licence:      GPL - http://www.gnu.org/copyleft/gpl.html
 *
 * Copyright (c) 2009-2012, The University of Melbourne, Australia
 */

package cloudsim.distributions;

import org.apache.commons.math3.distribution.UniformRealDistribution;

import java.util.Random;

/**
 * A pseudo random number generator following the
 * <a href="https://en.wikipedia.org/wiki/Uniform_distribution_(continuous)">
 * Uniform continuous distribution</a>.
 *
 * @author Marcos Dias de Assuncao
 * @since CloudSim Toolkit 1.0
 */
public class UniformDistr implements ContinuousDistribution {

    /**
     * The internal uniform pseudo random number generator.
     */
    private final UniformRealDistribution numGen;

    /**
     * Creates new uniform pseudo random number generator.
     *
     * @param min minimum value
     * @param max maximum value
     */
    public UniformDistr(double min, double max) {
        numGen = new UniformRealDistribution(min, max);
    }

    /**
     * Creates new uniform pseudo random number generator.
     *
     * @param min  minimum value
     * @param max  maximum value
     * @param seed simulation seed to be used
     */
    public UniformDistr(double min, double max, long seed) {
        this(min, max);
        numGen.reseedRandomGenerator(seed);
    }

    @Override
    public double sample() {
        return numGen.sample();
    }

    /**
     * Generates a new pseudo random number based on the generator and values provided as
     * parameters.
     *
     * @param rd  the random number generator
     * @param min the minimum value
     * @param max the maximum value
     * @return the next random number in the sequence
     */
    public static double sample(Random rd, double min, double max) {
        if (min >= max) {
            throw new IllegalArgumentException("Maximum must be greater than the minimum.");
        }

        return (rd.nextDouble() * (max - min)) + min;
    }

    /**
     * Sets the random number generator's seed.
     *
     * @param seed the new seed for the generator
     */
    public void setSeed(long seed) {
        numGen.reseedRandomGenerator(seed);
    }

}